Graphene oxide nanocomposite membrane having improved gas barrier characteristics and method for manufacturing the same

ABSTRACT

The present invention relates to a technique of manufacturing a graphene oxide nanocomposite membrane in which 3 μm to 5 μm-sized graphene oxide is coated with a thickness of 10 nm or more on various supports, or a graphene oxide nanocomposite membrane having a structure in which graphene oxide is inserted into a polymer. The graphene oxide nanocomposite membrane manufactured according to the present invention has excellent barrier characteristics against various gases even when graphene oxide, of which the size is controlled to 3 μm to 5 μm, is coated as a nanometer-thick thin film on various supports or the graphene oxide nanocomposite membrane has a simple structure in which graphene oxide is inserted into a polymer, and thus the graphene oxide nanocomposite membrane can be applied to the packaging of display devices, food, and medical products.

TECHNICAL FIELD

The present invention relates to a graphene oxide nanocomposite membranewith improved gas barrier characteristics and a method for manufacturingthe same. More specifically, the present invention relates to a methodof manufacturing a nanocomposite membrane including 3 μm to 50 μm-sizedgraphene oxide coated to a thickness of 10 nm or more on varioussupports, or a graphene oxide nanocomposite membrane having a structurein which graphene oxide is inserted into a polymer, wherein thenanocomposite membranes exhibit excellent barrier characteristicsagainst various gases and thus can be applied to packaging of displaydevices, food and medical products.

BACKGROUND ART

Graphene is a substance composed of a single carbon atom layer in theform of a hexagonal honeycomb, which has most been in the highlight inindustry and academia since it was first discovered in 2004, because itis quite interesting and exhibits excellent physical and chemicalproperties owing to the structural characteristic, so-called“two-dimensional lamella structure”. That is, graphene is the thinnestsubstance in the world, but has 200 times or more stronger mechanicalproperties than steel, 100 times or more higher current permeabilitythan copper and 100 times or more faster electron mobility than silicon.In particular, graphene is known to exhibit excellent barriercharacteristics against gas and ion molecules owing to superiormechanical strength in spite of being a single atomic layer.

However, excellent barrier characteristics against gas and ion moleculesof graphene can be only realized by a graphene structure that is freefrom defects. When defects are generated in graphene, gas and ionmolecules are easily permeated into defective graphene parts andinherent barrier characteristics thereof are thus lost. For this reason,when graphene is formed as a thin film, disadvantageously, it cannotmaintain barrier characteristics against gas and ion molecules.

A variety of technologies related to barrier characteristics of grapheneagainst gas and ion molecules have been developed. Recently, there wasmade an attempt to produce a graphene laminate barrier film including atleast one graphene laminate including a hydrophilic graphene layer and ahydrophobic graphene layer, wherein the graphene layer has a controlledthickness of 0.01 μm to 1,000 μm, and apply the same to food packagingusing barrier characteristics thereof. However, the structure of thegraphene laminate film is slightly complicated and only data showingoxygen and water vapor permeability is shown and barrier characteristicsthereof against various gases are not known to date (Patent Document 1).

In addition, graphene/polymer composite protective membranes including aplurality of graphene layers and a plurality of polymer layers betweenthe respective graphene layers are known, but it is only disclosed thatthe graphene composite membranes have complex structures and areapplicable as gas and water barriers, and detailed results associatedwith gas barrier characteristics of the graphene composite membranes arenot disclosed and practical application of the graphene compositemembranes to the industry is limited (Patent Document 2).

In addition, a gas diffusion barrier including a polymer matrix andfunctionalized graphene having a surface area of 300 to 2,600 m²/g and abulk density of 40 to 0.1 kg/m³ is also known. The gas diffusion barrieris characterized in that the surface area and bulk density offunctionalized graphene are controlled. The gas diffusion barrier is athick membrane in which functionalized graphene is dispersed in thepolymer matrix. In a case in which the gas diffusion barrier is a thinfilm, whether or not the gas diffusion barrier has gas barriercharacteristics cannot be expected, and actions and effects demonstratedby qualitative data associated with gas barrier characteristics are notdescribed in detail (Patent Document 3).

In addition, research on graphene/polyurethane nanocomposites in whichgraphite oxide as a nano-filler is incorporated into thermoplasticpolyurethane by melt mixing, solution blending or simultaneouspolymerization, and gas barrier characteristics thereof is also known.Barrier characteristics against a nitrogen gas depending on the amountof graphene present as a filler in thermoplastic polyurethane was found,but barrier characteristics against various gases depending on controlof the size of graphene oxide and of thickness of graphene oxide filmare not known (Non-patent Document 1).

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1. Korean Patent Laid-open Publication No.    10-2014-0015926-   Patent Document 2. Korean Patent Laid-open Publication No.    10-2013-0001705-   Patent Document 3. US Patent Laid-open Publication No. US    2010/0096595

Non-Patent Document

-   Non-patent Document 1. Hyunwoo Kim et al., Chem. Mater. 22,    3441-3450(2010)

DISCLOSURE Technical Problem

Therefore, it is an object of the present invention to provide agraphene oxide nanocomposite membrane which exhibits excellent gasbarrier characteristics against various gases, although it includesgraphene oxide with a controlled size coated in the form of a nano-scalethin film on a support, or has a simple structure in which grapheneoxide is inserted into a polymer, and a method of manufacturing thesame.

Technical Solution

In accordance with an aspect of the present invention, the above andother objects can be accomplished by the provision of a graphene oxidenanocomposite membrane with gas barrier characteristics including asupport and a coating layer including 3 μm to 50 μm-sized graphene oxidecoated to a thickness of 10 nm or more on the support and havingnanopores.

The support may include any one selected from the group consisting ofpolymer, ceramic, glass, paper and metal layers.

The polymer may include any one selected from the group consisting ofpolyester, polyolefin, polyvinyl chloride, polyurethane, polyacrylate,polycarbonate, polytetrafluoroethylene, polysulfone, polyether sulfone,polyimide, polyether imide, polyamide, polyacrylonitrile, celluloseacetate, cellulose triacetate and polyvinylidene fluoride.

The ceramic may include any one selected from the group consisting ofalumina, magnesia, zirconia, silicon carbide, tungsten carbide andsilicon nitride.

The metal layer may be a metal foil, a metal sheet or a metal film.

The metal layer may include any one material selected from the groupconsisting of copper, nickel, iron, aluminum and titanium.

The graphene oxide may be functionalized graphene oxide in which ahydroxyl group, a carboxyl group, a carbonyl group or an epoxy grouppresent in graphene oxide is converted into an ester group, an ethergroup, an amide group or an amino group.

The nanopores may have a mean diameter of 0.5 nm to 1.0 nm.

The coating layer may include graphene oxide including a single layer ormultiple layers.

The graphene oxide including a single layer may have a thickness of 0.6nm to 1 nm.

In another aspect of the present invention, provided is a graphene oxidenanocomposite membrane with gas barrier characteristics having astructure in which graphene oxide is inserted into a polyethylene glycoldiacrylate or polyethylene glycol dimethacrylate polymer.

The graphene oxide may have a size of 100 to 1000 nm.

The graphene oxide may be present in an amount of 5% by weight in thenanocomposite membrane.

In another aspect of the present invention, provided is a display deviceincluding the graphene oxide nanocomposite membrane with gas barriercharacteristics.

In another aspect of the present invention, provided is a food packagingmaterial including the graphene oxide nanocomposite membrane with gasbarrier characteristics.

In another aspect of the present invention, provided is a medicalproduct packaging material including the graphene oxide nanocompositemembrane with gas barrier characteristics.

In another aspect of the present invention, provided is a method ofmanufacturing a graphene oxide nanocomposite membrane with gas barriercharacteristics including i) dispersing graphene oxide in distilledwater and treating the dispersion with an ultrasonic grinder for 0.1 to6 hours to obtain a graphene oxide dispersion, ii) centrifuging thedispersion to form graphene oxide having a controlled size of 3 μm to 50μm, iii) dispersing the graphene oxide formed in step ii) in distilledwater again to obtain a graphene oxide dispersion, and iv) coating asupport with the dispersion obtained in step iii) to form a coatinglayer having nanopores.

The graphene oxide may be functionalized graphene oxide in which ahydroxyl group, a carboxyl group, a carbonyl group or an epoxy grouppresent in graphene oxide is converted into an ester group, an ethergroup, an amide group or an amino group.

The support may include any one selected from the group consisting ofpolymer, ceramic, glass, paper and metal layers.

The polymer may include any one selected from the group consisting ofpolyester, polyolefin, polyvinyl chloride, polyurethane, polyacrylate,polycarbonate, polytetrafluoroethylene, polysulfone, polyether sulfone,polyimide, polyether imide, polyamide, polyacrylonitrile, celluloseacetate, cellulose triacetate and polyvinylidene fluoride.

The ceramic may include any one selected from the group consisting ofalumina, magnesia, zirconia, silicon carbide, tungsten carbide andsilicon nitride.

The metal layer may be a metal foil, a metal sheet or a metal film.

The metal layer may include any one material selected from the groupconsisting of copper, nickel, iron, aluminum and titanium.

The coating may be carried out by any one method selected from the groupconsisting of direct evaporation, transfer, spin coating and spraycoating.

The spin coating may be conducted three to ten times.

The nanopores may have a mean diameter of 0.5 nm to 1.0 nm.

The coating layer may include graphene oxide including a single layer ormultiple layers.

The graphene oxide including a single layer may have a thickness of 0.6nm to 1 nm.

Effects of the Invention

The graphene oxide nanocomposite membrane manufactured according to thepresent invention has excellent barrier characteristics against variousgases even when graphene oxide, the size of which is controlled to 3 μmto 50 μm, is coated as a nanometer-thick thin film on various supportsor the graphene oxide nanocomposite membrane has a simple structure inwhich graphene oxide is inserted into a polymer, and thus the grapheneoxide nanocomposite membranes can be applied to the packaging of displaydevices, food and medical products.

DESCRIPTION OF DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 shows a structure of graphene oxide and a structure offunctionalized graphene oxide;

FIG. 2 is a transmission electron microscope (TEM) image showinggraphene oxide having a controlled size according to Example 1;

FIG. 3 is an image showing a graphene oxide nanocomposite membraneproduced in Example 1;

FIG. 4 is a transmission electron microscope (TEM) image showing across-section of a graphene oxide film coated on a polymer support (PES)according to Example 1;

FIG. 5 is an image showing a graphene oxide nanocomposite membranedepending on the content of graphene oxide produced in Example 2(graphene oxide size: 270 nm);

FIG. 6 is a scanning electron microscope (SEM) image showing a grapheneoxide nanocomposite membrane depending on the content of graphene oxideproduced in Example 2 (graphene oxide size: 270 nm).

FIG. 7 is an image showing a graphene oxide nanocomposite membranedepending on the size of graphene oxide produced in Example 2 (grapheneoxide content: 4% by weight);

FIG. 8 is a schematic view showing a configuration of a constantpressure/variable volume gas measurement device equipped with a gaschromatography apparatus;

FIG. 9 is a graph showing gas barrier characteristics and gas permeationpressures of an ultrathin film graphene oxide film depending on the sizeof graphene oxide;

FIG. 10 is a scanning electron microscope (SEM) image showing a grapheneoxide film with a thickness of about 5 μm produced by ordinary vaporfiltration;

FIG. 11 is a graph showing gas barrier characteristics of the grapheneoxide film produced by ordinary vapor filtration depending on size ofgraphene oxide;

FIG. 12 is a graph showing theoretical gas barrier characteristicsdepending on the size of graphene oxide and the thickness of thegraphene oxide thin film;

FIG. 13 is a graph showing oxygen permeability of graphene oxidenanocomposite membrane depending on the content of graphene oxideproduced in Example 2 (graphene oxide size: 270 nm); and

FIG. 14 is a graph showing oxygen permeability of graphene oxidenanocomposite membrane depending on the size of graphene oxide producedin Example 2 (graphene oxide content: 4% by weight).

BEST MODE

Hereinafter, the nanocomposite membrane in which 3 μm to 50 μm-sizedgraphene oxide is coated to a thickness of 10 nm or more on varioussupports and the method of manufacturing the same according to thepresent invention will be described in detail with reference to theannexed drawings.

First, the support can be made of a variety of substances which functionas a reinforcing material to support the coating layer and contact thecoating layer, and the support may include any one selected from thegroup consisting of polymer, ceramic, glass, paper and metal layers. Inparticular, the polymer includes any one selected from the groupconsisting of polyester, polyolefin, polyvinyl chloride, polyurethane,polyacrylate, polycarbonate, polytetrafluoroethylene, polysulfone,polyether sulfone, polyimide, polyether imide, polyamide,polyacrylonitrile, cellulose acetate, cellulose triacetate andpolyvinylidene fluoride, but is not limited thereto. Among thesepolymers, polyether sulfone is more preferably used, but the polymer isnot limited thereto.

In addition, the ceramic support includes any one selected from thegroup consisting of alumina, magnesia, zirconia, silicon carbide,tungsten carbide, silicon nitride and silicon nitride, and the ceramicsupport is preferably alumina or silicon carbide.

In addition, when the support is formed of a metal layer, the metallayer may have various forms such as a metal foil, a metal sheet and ametal film. The material for the metal layer may include any oneselected from the group consisting of copper, nickel, iron, aluminum andtitanium.

Next, the coating layer having nanopores in which 3 μm to 50 μm-sizedgraphene oxide is coated to a thickness of nm or more on varioussupports will be described in detail.

The graphene oxide used for the present invention can be mass-producedby oxidizing graphite using an oxidant and includes a hydrophilicfunctional group such as a hydroxyl group, a carboxyl group, a carbonylgroup or an epoxy group. At present, most graphene oxide is manufacturedby Hummers' method [Hummers, W. S. & Offeman, R. E. Preparation ofgraphite oxide. J. Am. Chem. Soc. 80. 1339(1958)] or a partiallymodified version of Hummers' method. In the present invention, grapheneoxide is obtained by Hummers' method as well.

In addition, the graphene oxide of the present invention may befunctionalized graphene oxide in which a hydrophilic functional groupsuch as a hydroxyl group, a carboxyl group, a carbonyl group or an epoxygroup present in the graphene oxide is converted into an ester group, anether group, an amide group or an amino group by chemical reaction withother compounds and examples thereof include functionalized grapheneoxide in which a carboxyl group of graphene oxide is reacted withalcohol and is thus converted into an ester group, functionalizedgraphene oxide in which a hydroxyl group of graphene oxide is reactedwith alkyl halide and is thus converted into an ester group,functionalized graphene oxide in which a carboxyl group of grapheneoxide is reacted with alkyl amine and is thus converted into an amidegroup, and functionalized graphene oxide in which an epoxy group ofgraphene oxide is ring-opening reacted with alkyl amine and is thusconverted into an amino group.

Regarding the size of graphene oxide, as the size thereof increases, gasbarrier characteristics increase. When the size thereof is less than 50μm, gas permeation is obtained, opposite to barrier characteristics. Inthe present invention, barrier characteristics against gases can beimproved by controlling the thickness of graphene oxide, although thesize of graphene oxide is controlled below 50 μm. Thus, the size of thegraphene oxide is controlled to 50 μm or less. In a case in which thesize of graphene oxide is excessively small, it is difficult to maintainbarrier characteristics against various gases having different molecularsizes. Accordingly, the size should be controlled to 3 μm or more. Thatis, in order for the graphene oxide thin film according to the presentinvention to exhibit excellent barrier characteristics against variousgases having different molecular sizes, the size of graphene oxide ispreferably controlled within the range of 3 μm to 50 μm, particularlypreferably the range of 3 μm to 10 μm because graphene oxide exhibitsexcellent gas barrier characteristics although it is formed as anultrathin film. FIG. 1 shows a structure of graphene oxide obtained byHummers' method from graphite and a structure of functionalized grapheneoxide produced by reacting graphene oxide with other compounds.

Meanwhile, according to the present invention, the graphene oxidecoating layer formed on various supports includes graphene oxide havinga single layer or multiple layers, and graphene oxide having a singlelayer has a thickness of 0.6 nm to 1 nm. In addition, graphene oxidehaving a single layer may be laminated to form graphene oxide havingmultiple layers. An additional movement route is formed between grainboundaries due to small distance between graphene oxide layers of about0.34 nm to 0.5 nm, and barrier characteristics against various gaseshaving different molecular sizes can be improved by controlling the poreand channel size between grain boundaries. Accordingly, the grapheneoxide coating layer more preferably includes graphene oxide havingmultiple layers.

As the thickness of the graphene oxide coating layer increases, gasbarrier characteristics thereof are improved. As described above, in thepresent invention, when the size of graphene oxide is controlled to therange of 3 μm to 50 μm, although a graphene oxide coating layer isformed as an ultrathin film having a thickness of at least 10 nm, it canexhibit gas barrier characteristics. Accordingly, the thickness ofgraphene oxide coating layer is preferably 10 nm or more. Furthermore,the graphene oxide coating layer forms nanopores having a mean diameterof 0.5 nm to 1.0 nm.

In addition, in addition to the gas barrier graphene oxide nanocompositemembrane including graphene oxide coated on various supports includingpolymer supports as described above, the present invention provides agraphene oxide nanocomposite membrane with gas barrier characteristicshaving a structure in which graphene oxide is inserted into polyethyleneglycol diacrylate or a polyethylene glycol dimethacrylate polymer.

That is, in the polymerization, into a polymer, of the polyethyleneglycol diacrylate or polyethylene glycol dimethacrylate macromer havinga carbon-carbon double bond at an end thereof, and in the formation of across-linked structure, graphene oxide as a filler is inserted into thepolymer, thereby further improving gas barrier effects. In this case,the polyethylene glycol diacrylate or polyethylene glycol dimethacrylatemacromer preferably has a number average molecular weight (Mn) of 250 to1000 in terms of UV polymerization using a photoinitiator and formationof a cross-linked structure.

In addition, the graphene oxide preferably has a size of 100 to 1,000nm. When the size of graphene oxide is less than 100 nm, gas barriercharacteristics may be deteriorated and when the size thereof exceeds1,000 nm, the graphene oxide may not be uniformly inserted and dispersedin the polyethylene glycol diacrylate or polyethylene glycoldimethacrylate polymer having a cross-linked structure.

In addition, the amount of graphene oxide present in the graphene oxidenanocomposite membrane with gas barrier characteristics having astructure in which graphene oxide is inserted into the polyethyleneglycol diacrylate or polyethylene glycol dimethacrylate polymer ispreferably less than 5 wt % because an effect of reducing gaspermeability can be maximized.

In addition, the present invention provides a method of manufacturing agraphene oxide nanocomposite membrane with gas barrier characteristics,including: i) dispersing graphene oxide in distilled water and treatingthe dispersion with an ultrasonic grinder for 0.1 to 6 hours to obtain agraphene oxide dispersion, ii) centrifuging the dispersion to formgraphene oxide having a controlled size of 3 μm to 50 μm, iii)dispersing the graphene oxide formed in step ii) in distilled wateragain to obtain a graphene oxide dispersion, and iv) coating a supportwith the dispersion obtained in step iii) to form a coating layer havingnanopores.

The graphene oxide in step i) may be functionalized graphene oxide inwhich a hydroxyl group, a carboxyl group, a carbonyl group or an epoxygroup present in graphene oxide is converted into an ester group, anether group, an amide group, or an amino group.

In addition, in step i), the graphene oxide is dispersed in distilledwater and then treated with an ultrasonic grinder for 0.1 to 6 hours toobtain a graphene oxide dispersion, thereby improving dispersibility ofgraphene oxide in the dispersion. In addition, the dispersion obtainedin step iii) is a 0.01 to 0.5 wt % aqueous graphene oxide solution whichhas pH adjusted to 10.0 with a 1M aqueous sodium hydroxide solution.When the concentration of the aqueous graphene oxide solution is lessthan 0.01 wt %, it is disadvantageously difficult to obtain the uniformcoating layer and, when the concentration thereof exceeds 0.5 wt %,coating cannot be disadvantageously efficiently conducted due toexcessively high viscosity. Thus, the concentration of the aqueousgraphene oxide solution is preferably 0.01 to 0.5 wt %.

In addition, in step iv), the support can be made of a variety ofsubstances which function as a reinforcing material to support thecoating layer and contact the coating layer, and the support may be madeof any one selected from the group consisting of polymer, ceramic,glass, paper and metal layers. In particular, the polymer includes anyone selected from the group consisting of polyester, polyolefin,polyvinyl chloride, polyurethane, polyacrylate, polycarbonate,polytetrafluoroethylene, polysulfone, polyether sulfone, polyimide,polyether imide, polyamide, polyacrylonitrile, cellulose acetate,cellulose triacetate and polyvinylidene fluoride, but the polymer is notlimited thereto. Among these polymers, polyether sulfone is morepreferably used, but the polymers are not limited thereto.

In addition, the ceramic support includes any one selected from thegroup consisting of alumina, magnesia, zirconia, silicon carbide,tungsten carbide and silicon nitride, and the ceramic support ispreferably alumina or silicon carbide.

In addition, when the support is formed of a metal layer, the metallayer may have various forms such as a metal foil, a metal sheet or ametal film. The material for the metal layer may include any oneselected from the group consisting of copper, nickel, iron, aluminum andtitanium.

In step iv), any well-known coating method may be used for forming thecoating layer without imitation and the coating method is preferablyselected from the group consisting of direct evaporation, transfer, spincoating method, and spray coating. Among these methods, spin coating ismore preferable because a uniform coating layer can be easily obtained.

Spin coating is preferably conducted 3 to 10 times. When spin coating isconducted less than three times, the function of a gas barrier layercannot be disadvantageously obtained and, when the spin coating isconducted 10 times or more, a uniform coating layer cannot bedisadvantageously obtained due to excessive thickness of the coatinglayer.

In step iv), the coating layer may include graphene oxide with a singlelayer or multiple layers and the graphene oxide with a single layer mayhave a thickness of 0.6 nm to 1 nm. The graphene oxide coating layerforms nanopores having a mean diameter of 0.5 nm to 1.0 nm.

MODE FOR INVENTION

Hereinafter, specific examples will be described in detail.

Example 1

Graphene oxide prepared by Hummers' method was distilled in distilledwater and treated with an ultrasonic grinder for 3 hours to obtain agraphene oxide dispersion. The dispersion was centrifuged to formgraphene oxide having a controlled size of 3 μm and the graphene oxidewas dispersed in distilled water again to obtain a 0.1 wt % aqueousgraphene oxide solution having a pH adjusted to 10.0 with a 1M aqueoussodium hydroxide solution. 1 mL of the aqueous graphene oxide solutionwas spin-coated on a porous polyether sulfone (PES) support 5 times toproduce a graphene oxide nanocomposite membrane having a graphene oxidecoating layer with a thickness of 10 nm.

Example 2

A polyethylene glycol diacrylate (PEGDA) macromer (having number averagemolecular weight of 250) was mixed with deionized water in a weightratio of 7:3 and stirred for 12 hours to obtain a homogenous solution.1% by weight of graphene oxide prepared by Hummers' method and 0.1% byweight of hydroxycyclohexyl phenyl ketone as a photoinitiator withrespect to the weight of the PEGDA macromer were added to the solution,and the resulting mixture was ultrasonicated for 2 hours and stirred for24 hours to obtain a precursor solution. The precursor solution was caston a glass plate and 312 nm UV was applied thereto under a nitrogenatmosphere for 5 minutes to produce a graphene oxide nanocompositemembrane (at this time, graphene oxide had a size of 270 nm or 800 nmand the content thereof was changed to 1, 2, 3, and 4% by weight withrespect to the weight of the PEGDA macromer).

Test Example

Gas barrier characteristics of graphene oxide nanocomposite membranesproduced in Examples 1 and 2 were measured with a constantpressure/variable volume gas measurement device equipped with a gaschromatography apparatus.

FIG. 2 shows a transmission electron microscope (TEM) image of grapheneoxide obtained by centrifuging a graphene oxide dispersion according toan example of the present invention and it can be seen that the sizethereof was controlled to about 3 μm.

The camera image of FIG. 3 shows that the graphene oxide nanocompositemembrane produced according to an example of the present inventionincludes a graphene oxide coating layer formed on a polyether sulfonesupport.

FIG. 4 is a transmission electron microscope (TEM) image showing across-section of a graphene oxide film coated to a thickness of 10 nm ona porous polyether sulfone (PES) support according to an example of thepresent invention. From FIG. 4, it can be seen that graphene oxide wasuniformly laminated.

Meanwhile, as can be seen from the image of FIG. 5, showing a grapheneoxide nanocomposite membrane depending on the content of graphene oxideproduced in Example 2 (size of graphene oxide: 270 nm), as the contentof graphene oxide increases, the color becomes darker. This means thatthe content of graphene oxide increases and graphene oxide is uniformlydispersed and inserted in a PEGDA polymer having a cross-linkedstructure.

In addition, as can be seen from the scanning electron microscope (SEM)image of FIG. 6, showing a graphene oxide nanocomposite membranedepending on the content of graphene oxide produced in Example 2 (sizeof graphene oxide: 270 nm), a PEGDA polymer (pristine PEG) membranecontaining no graphene oxide has a smooth surface, whereas a compositemembrane containing graphene oxide (2 wt % GO and 4 wt % GO) has a layerstructure including graphene oxide.

Furthermore, as can be seen from the image of FIG. 7, showing a grapheneoxide nanocomposite membrane depending on the size of graphene oxideproduced in Example 2 (graphene oxide content: 4% by weight), althoughthe size of graphene oxide increases from 270 nm to 800 nm, grapheneoxide is uniformly dispersed and inserted in a PEGDA polymer having across-linked structure.

In addition, gas barrier characteristics of the graphene oxide filmaccording to the present invention were evaluated with a constantpressure/variable volume gas measurement device equipped with a gaschromatography apparatus, as shown in FIG. 8. From FIG. 9, it can beseen that, as the size of graphene oxide increases, a pressure at whichgas permeation begins gradually increases, in particular, in a case inwhich a thin film is produced using graphene oxide having a size of 3.0μm (=3000 nm), gas cannot be permeated even upon application of arelatively high pressure (180 mbar).

Meanwhile, in order to confirm the size of graphene oxide and thethickness of the graphene oxide thin film which have an effect on gasbarrier characteristics of the graphene oxide thin film depending onpresence of the support, a graphene oxide film having no support wasproduced by an ordinary vapor filtration method. FIG. 10 shows ascanning electron microscope (SEM) image of a graphene oxide film with athickness of about 5 μm produced by an ordinary vapor filtration method.As can be seen from the image, graphene oxide having a two-dimensionalstructure was laminated without any voids.

In addition, FIG. 11 shows gas barrier characteristics of a grapheneoxide film, in which graphene oxide was controlled to have certain sizes(0.5, 1.0 and 5.0 μm), produced by an ordinary vapor filtration method.As can be seen from FIG. 11, as the size of graphene oxide increases,gas permeability was changed to gas barrier characteristics and inparticular, gas barrier characteristics are excellent, when the size ofgraphene oxide is 3.0 μm or more. This indicates that gas barriercharacteristics can be improved by controlling the size of grapheneoxide without any support.

Furthermore, FIG. 12 is a graph showing theoretical gas permeationchannel lengths of graphene oxide films having various sizes at the samethickness. As can be seen from FIG. 12, as the size of graphene oxideincreases at the same thickness, the gas permeation channel lengthgradually increases, and when a film is produced using graphene oxidehaving a certain size (3.0 μm), gas permeation channel length increasesand superior gas barrier characteristics are obtained. This correspondsto measurement results of Test Example according to the presentinvention.

In addition, FIG. 13 shows a graph showing oxygen permeability of thegraphene oxide nanocomposite membrane depending on the content ofgraphene oxide produced in Example 2 (graphene oxide size: 270 nm). Ascan be seen from FIG. 13, as the content of graphene oxide increases,oxygen permeability gradually decreases, and in particular, when theamount of graphene oxide present in the graphene oxide nanocompositemembrane is 4% by weight, oxygen permeability is decreased to 83% ascompared to the PEGDA polymer (pristine PEG) membrane containing nographene oxide.

In addition, FIG. 14 is a graph showing oxygen permeability of agraphene oxide nanocomposite membrane depending on the size of grapheneoxide produced in Example (graphene oxide content: 4% by weight). As canbe seen from FIG. 14, as the size of graphene oxide increases, gasbarrier characteristics are gradually improved, and in particular, whenthe size of graphene oxide inserted into the graphene oxidenanocomposite membrane is 800 nm, oxygen permeability was decreased to90% as compared to the PEGDA polymer (pristine PEG) membrane containingno graphene oxide.

INDUSTRIAL APPLICABILITY

Accordingly, the graphene oxide nanocomposite membrane manufacturedaccording to the present invention has excellent barrier characteristicsagainst various gases even when graphene oxide, the size of which iscontrolled to 3 μm to 5 μm, is coated as a nanometer-thick thin film onvarious supports or the graphene oxide nanocomposite membrane has asimple structure in which graphene oxide is inserted into a polymer, andthus the graphene oxide nanocomposite membrane can be applied to thepackaging of display devices, food and medical products.

1. A graphene oxide nanocomposite membrane with gas barriercharacteristics comprising: a support; and a coating layer comprising 3μm to 50 μm-sized graphene oxide coated to a thickness of 10 nm or moreon the support and having nanopores.
 2. The graphene oxide nanocompositemembrane with gas barrier characteristics according to claim 1, whereinthe support comprises any one selected from the group consisting ofpolymer, ceramic, glass, paper and metal layers.
 3. The graphene oxidenanocomposite membrane with gas barrier characteristics according toclaim 2, wherein the polymer comprises any one selected from the groupconsisting of polyester, polyolefin, polyvinyl chloride, polyurethane,polyacrylate, polycarbonate, polytetrafluoroethylene, polysulfone,polyether sulfone, polyimide, polyether imide, polyamide,polyacrylonitrile, cellulose acetate, cellulose triacetate andpolyvinylidene fluoride.
 4. The graphene oxide nanocomposite membranewith gas barrier characteristics according to claim 2, wherein theceramic comprises any one selected from the group consisting of alumina,magnesia, zirconia, silicon carbide, tungsten carbide and siliconnitride.
 5. The graphene oxide nanocomposite membrane with gas barriercharacteristics according to claim 2, wherein the metal layer is a metalfoil, a metal sheet or a metal film.
 6. The graphene oxide nanocompositemembrane with gas barrier characteristics according to claim 5, whereinthe metal layer comprises any one material selected from the groupconsisting of copper, nickel, iron, aluminum and titanium.
 7. Thegraphene oxide nanocomposite membrane with gas barrier characteristicsaccording to claim 1, wherein the graphene oxide is functionalizedgraphene oxide in which a hydroxyl group, a carboxyl group, a carbonylgroup or an epoxy group present in graphene oxide is converted into anester group, an ether group, an amide group or an amino group.
 8. Thegraphene oxide nanocomposite membrane with gas barrier characteristicsaccording to claim 1, wherein the nanopores have a mean diameter of 0.5nm to 1.0 nm.
 9. The graphene oxide nanocomposite membrane with gasbarrier characteristics according to claim 1, wherein the coating layercomprises graphene oxide including a single layer or multiple layers.10. The graphene oxide nanocomposite membrane with gas barriercharacteristics according to claim 9, wherein the graphene oxideincluding a single layer has a thickness of 0.6 nm to 1 nm.
 11. Agraphene oxide nanocomposite membrane with gas barrier characteristicshaving a structure in which graphene oxide is inserted into apolyethylene glycol diacrylate or polyethylene glycol dimethacrylatepolymer.
 12. The graphene oxide nanocomposite membrane with gas barriercharacteristics according to claim 11, wherein the graphene oxide has asize of 100 to 1000 nm.
 13. The graphene oxide nanocomposite membranewith gas barrier characteristics according to claim 11, wherein grapheneoxide is present in an amount of 5% by weight in the nanocompositemembrane.
 14. A method of manufacturing a graphene oxide nanocompositemembrane with gas barrier characteristics comprising: i) dispersinggraphene oxide in distilled water and treating the dispersion with anultrasonic grinder for 0.1 to 6 hours to obtain a graphene oxidedispersion; ii) centrifuging the dispersion to form graphene oxidehaving a controlled size of 3 μm to 50 μm; iii) dispersing the grapheneoxide formed in step ii) in distilled water again to obtain a grapheneoxide dispersion; and iv) coating a support with the dispersion obtainedin step iii) to form a coating layer having nanopores.
 15. The methodaccording to claim 14, wherein the graphene oxide is functionalizedgraphene oxide in which a hydroxyl group, a carboxyl group, a carbonylgroup or an epoxy group present in graphene oxide is converted into anester group, an ether group, an amide group or an amino group.
 16. Themethod according to claim 14, wherein the support comprises any oneselected from the group consisting of polymer, ceramic, glass, paper andmetal layers.
 17. The method according to claim 16, wherein the polymercomprises any one selected from the group consisting of polyester,polyolefin, polyvinyl chloride, polyurethane, polyacrylate,polycarbonate, polytetrafluoroethylene, polysulfone, polyether sulfone,polyimide, polyether imide, polyamide, polyacrylonitrile, celluloseacetate, cellulose triacetate and polyvinylidene fluoride.
 18. Themethod according to claim 16, wherein the ceramic comprises any oneselected from the group consisting of alumina, magnesia, zirconia,silicon carbide, tungsten carbide and silicon nitride.
 19. The methodaccording to claim 16, wherein the metal layer is a metal foil, a metalsheet or a metal film.
 20. The method according to claim 19, wherein themetal layer comprises any one material selected from the groupconsisting of copper, nickel, iron, aluminum and titanium.
 21. Themethod according to claim 14, wherein the coating is carried out by anyone method selected from the group consisting of direct evaporation,transfer, spin coating and spray coating.
 22. The method according toclaim 21, wherein the spin coating is conducted three to ten times. 23.The method according to claim 14, wherein the nanopores have a meandiameter of 0.5 nm to 1.0 nm.
 24. The method according to claim 14,wherein the coating layer comprises graphene oxide including a singlelayer or multiple layers.
 25. The method according to claim 24, whereinthe graphene oxide including a single layer has a thickness of 0.6 nm to1 nm.
 26. A display device comprising the graphene oxide nanocompositemembrane with gas barrier characteristics according to claim
 1. 27. Afood packaging material comprising the graphene oxide nanocompositemembrane with gas barrier characteristics according to claim
 1. 28. Amedical product packaging material comprising the graphene oxidenanocomposite membrane with gas barrier characteristics according toclaim 1.